A moisture meter is an ideal tool for locating hidden water leaks behind drywall and checking moisture levels in wood and other materials. Here we will review some of the best moisture meters for home inspections, show you how to use them, and explain the different types.
- Why use a moisture meter?
- Types of moisture meters
- Thermal imaging
- The best pin-type moisture meters
- General Tools MMD4E
- Protimeter Digital Mini BLD5702
- The best pinless moisture meters
- General Tools MMD7NP
- Protimeter Aquant BLD5765
- The best all-in-one moisture meters
- General Tools MMH800
- Protimeter BLD5365 Surveymaster
- The best thermal imaging moisture meters
- PerfectPrime IR0280 Thermal Imager
- FLIR MR160
- Commonly asked questions
- How do moisture meters work?
- Are moisture meters accurate?
- Can a moisture meter detect mold?
- What is an acceptable moisture reading for drywall?
- What is an acceptable moisture reading for wood?
Why use a moisture meter?
Leaks behind drywall and inside ceilings usually go by undetected until it’s too late. Not only does this excessive moisture cause mold outbreaks, but it also causes structural damage and deterioration that can cost thousands of dollars to repair.
A moisture meter can detect moisture problems early, or at the very least confirm that there is a problem. They can be used to get fast and accurate moisture level readings on materials such as drywall, wood, concrete, etc.
Types of moisture meters
When it comes to selecting a moisture meter, you will have four varieties to choose from. There are pin, pinless, all-in-one, and thermal imaging types.
Pin-type moisture meters have dual pins which penetrate the surface of the area you want to be tested. It only reads the moisture levels up to the point where the pins end. The reading level, which is given in %MC, is determined by the electrical resistance between the two pins.
The pin type can provide readings on any penetrable surface, therefore, using a pinless moisture meter would be better for impenetrable surfaces and for surface areas you don’t want to poke holes into.
Pinless moisture meters use an electromagnetic sensor pad to detect moisture levels up to 1.5″ deep in a non-invasive way. They are ideal for measuring moisture levels behind bathroom tiles, various types of flooring, and drywall.
Building inspectors, IAQ, and flooring specialists prefer the all-in-one types as they can take readings with and without pins.
A thermal imaging moisture meter uses infrared to find and detect water leaks, moisture, and even mold behind surfaces.
They are faster, more accurate, and allow you to find the exact location and size of the problem.
The best pin-type moisture meters
General Tools MMD4E
The General Tools MMD4E Pin-type Moisture Meter fits comfortably in your hand and has an LCD screen that gives clear readings.
The stainless steel pins will provide you with accurate readings on the moisture levels in sub-flooring, wood, concrete, ceilings, and drywall. Not only does it give you the moisture readings in percentages, but it also tells you if the moisture levels are low, mid-range, or high just in case you do not know the acceptable moisture percentage range for the material you are testing.
The MDD4E is powered by a 9-volt battery (included) and automatically powers down after 3 minutes of inactivity.
It’s a high-quality tool that enjoys consistently high ratings on Amazon.com and is the best low-cost pin-type moisture meter on the market.
The product has dimensions of 6.0″ x 2.6″ x 0.8″ and weighs 0.18 pounds.
Protimeter Digital Mini BLD5702
The Protimeter Digital BLD5702 Mini moisture meter is rugged, easy to use, and gives highly accurate moisture readings on a wide range of materials.
It also shows you the extent of the moisture penetration, while keeping track of the moisture levels and diagnoses the cause of the problem.
The Protimeter BLD5702 is powered by a 9-volt battery (included) and comes with a 2-year warranty.
It weighs 1.5 pounds, and has dimensions of 7.5″ x 2.75″ x 1.9″.
The best pinless moisture meters
General Tools MMD7NP
The General Tools MMD7NP Pinless Moisture Meter tests for moisture levels up to 3/4″ deep without damaging surface areas with pins.
It’s ideal for use on all types of wood, drywall, and even masonry surfaces.
Its features include a powerfully bright LCD screen so that you can see readings from various angles, a low battery indicator, a HOLD button, an out-of-range alarm, auto-calibrating, and a handy auto power-off function to preserve battery life.
The MMD7NP is powered by a 9-volt battery (included), weighs 0.25 pounds, and has dimensions of 1.13″ x 3″ x 6.5″.
Protimeter Aquant BLD5765
Not only is the Protimeter Aquant BLD5765 reliable, but it’s also very simple to use.
It gives highly accurate moisture readings on wood, ceilings, walls, concrete, floors, and even vinyl and ceramics.
A rugged design ensures excellent durability and the large display makes it easy to see the displayed readings.
The Protimeter Aquant BLD5765 comes with a 2-Year warranty, runs on a 9-volt battery (included), has dimensions of 7″ x 1.9″ x 2″, and weighs 15 ounces.
The best all-in-one moisture meters
General Tools MMH800
The General Tools MMH800 All-In-One Moisture Meter can be used as a pin-type and pinless moisture meter.
It’s renowned for its incredible accuracy, and apart from detecting moisture levels, it can also find the actual source of leaks.
The device comes with features such as the ability to check and display ambient temperatures and humidity in addition to a HOLD and auto power-off function. The MMH800 is the preferred moisture meter among many building inspectors and flood damage responders.
It includes a 9-volt battery, 2x sets of spare pins, and a lanyard.
The product weighs 1.95 pounds and has dimensions of 3.63″ x 8.13″ x 12″.
Protimeter BLD5365 Surveymaster
The Protimeter BLD5365 Surveymaster is undoubtedly one of the best moisture meters for professionals.
It is durable, features a clear, large backlit display, and has been ergonomically designed to be easily used with one hand.
And not only can it diagnose the source of the leak, the extent of the moisture problem, and monitor changes in the moisture levels, but it also distinguishes between moisture on the surface and sub-surface.
The Protimeter BLD5365 Surveymaster runs on a 9-volt battery (included) and has a 2-year warranty.
It has dimensions of 7.5″ x 2.75″ x 1.9″ and weighs 1.5 pounds.
The best thermal imaging moisture meters
PerfectPrime IR0280 Thermal Imager
The PerfectPrime IR0280 Thermal Imager shows heat signatures on and behind surface areas on a 32 x 32, 1024px touch screen.
It can provide a full analysis on temperatures as low as -22°F (-30) and as high as 1832 °F (1000 °C).
The thermal imager software runs on an Android operating system and gets periodically updated with new features. You can also live-stream to a computer screen and click on the pixels for the actual temperature readings.
It’s ideal for professional and home use and runs on a lithium-ion battery (included).
The FLIR MR160 is the ultimate moisture meter and is far more advanced than the aforementioned PerfectPrime IR0280.
It has an integrated pinless sensor and an external probe, which means that you can also use it as a pin and pinless moisture meter.
It’s portable enough to easily fit onto a toolbelt and rugged enough to last for many years. Better yet, it comes with a 2-year product warranty and an impressive 10-year warranty on the thermal detector.
As for its thermal imaging capabilities – it uses a Lepton thermal imager (80×60) and utilizes IGM (Advanced Infrared Guided Measurement Technology). What IGM does is pinpoint the exact location of moisture spots, so it’s a very handy feature.
Other features include color moisture alert, automatic image calibration, and the ability to store as many as 9999 images thermal images onto the device.
Then there is the free FLIR reporting software that you can use to analyze data and create detailed reports.
The thermal imager is ready to use straight out of the box and runs on a 3.7-volt Li-ion rechargeable battery that can power the device for 18 continuous hours. It weighs just under 11 ounces and has dimensions of 5.5″ x 2.9″ x 1.7″.
Commonly asked questions
How do moisture meters work?
Pin and pinless types work in different ways. Here we’ll cover both.
How do pin-type moisture meters work?
These types have two metal probes (pins) attached to the front end of the device that you use to penetrate the surface area of the material you want to test.
Electrical currents are sent between the two pins, and the amount of resistance given determines the moisture level. Also, the moisture levels are only measured up to the point where the pins end (3/4″ on average).
How do pinless-type moisture meters work?
Pinless moisture meters are non-invasive because they use an electromagnetic sensor pad that you hold against the surface of the material you want to be tested.
Some models can test up to 1.5″ beneath the surface.
Are moisture meters accurate?
The level of accuracy depends on several things:
Cheap moisture meters from unknown brands are more than likely to give highly inaccurate readings. But that does not imply that an accurate moisture meter has to be expensive. Just stick to well-known/trusted brands such as Delmhorst, General Tools, Protimeter, Wagner, etc.
Using it correctly:
The best moisture meter in the world will be of no good unless used correctly. Pin moisture meters, for example, can only be used on straight surface areas. Measuring an uneven surface is almost guaranteed to give a false reading. Always check the user manual for details on correct usage.
Selecting the correct moisture reading scale:
Moisture meters capable of taking readings from various types of materials have different reading scales. In other words, there is a specific reading scale for drywall, another for concrete, and another for wood. Always make sure you are using the correct reading scale for the material you are testing to ensure an accurate reading.
Always make sure that the material you are testing is dry on the surface – especially when using a pin-type because the electrical current could route through the surface water instead of the pins and give an incorrect reading as a result.
Damaged or rusted pins can interfere with the electrical current between the two pins on a pin-type. Likewise, a dented or badly scratched scanning plate on a pinless will also most likely give an incorrect moisture reading.
Never use a moisture meter with a low battery because that can affect the accuracy of the reading.
Can a moisture meter detect mold?
No, a moisture meter is not able to determine the physical presence of mold. What it can do is give you a clear indication of whether or not the moisture conditions are suitable for mold.
What is an acceptable moisture reading for drywall?
A moisture reading between 5 to 12% is considered normal, so anything above 12% means that there is a problem. Drywall with a moisture content between 13 and 16% can be saved if quick action is taken, but anything from 17% and above means that it’s unsalvageable.
What is an acceptable moisture reading for wood?
A 6 to 10% moisture level reading is normal for indoor wood. Anything from 20% and above is a serious problem.